blink reflex
A brainstem reflex elicited by stimulating the supraorbital nerve and recording from orbicularis oculi muscles bilaterally.
Full Definition
The blink reflex is a polysynaptic brainstem reflex that evaluates the functional integrity of the trigeminal and facial nerves along with their brainstem connections. The test involves electrical stimulation of the supraorbital branch of the trigeminal nerve while recording EMG responses from the orbicularis oculi muscles bilaterally. The response consists of an early R1 component (ipsilateral, oligosynaptic) and a late R2 component (bilateral, polysynaptic). Abnormalities can localize lesions to the trigeminal nerve, facial nerve, or brainstem tegmentum. The blink reflex is particularly useful in evaluating facial nerve disorders and brainstem pathology.
Usage
Usage note: Distinguish between R1 and R2 components and specify which side stimulated/recorded.
In Context
- "The blink reflex showed absent R1 and R2 responses on the left side, consistent with a proximal facial nerve lesion." — Cranial nerve reflex study